Capacity: At least 120GB. I'm ok with using a 128 GB memory card, but that would reduce my budget for the player from $350 to around $250 (to accommodate the cost of the card).

Budget: See above.

Use: Music only. Mostly listening at home, but not exclusively. I don't plan to use the player when commuting (I listen to Umano), or when working out (I have a Sansa Clip Zip for that). I don't care about video.

Type/Design: I don't care if it's DAP or PMP as long as sound quality and user interface are both very good. If the player has video capabilities which don't interfere with these aspects, it's fine.

Features:

Must

Very good sound quality. I'm not an audiophile, so the absolute best is not needed, but it needs to be at least as good as the X7.

Folder support, preferably with an option to completely disable database and ID3 tag indexing (a complete waste of time when my library is already properly structured using Artist\Album folder hierarchy).

No limit on the number of songs in the disk

FLAC & OGG support

EQ (preferably no more than 5 bands)

If the player relies on memory cards, it needs to support 128 GB in a single partition and use a file system that Windows supports

Highly desired

Decent volume. I'd be happy to find another player that can drive my Beyerdynamic DT990 Pro 250 OHM without having to connect an amplifier (the X7 was doing an ok job, so I normally didn't have to connect my FiiO E11)

Line out

Gapless

Mass storage support (MSC)

Nice to have

Built in speaker

Sound enhancements

Bluetooth

FM radio tuner

Don't need, don't care

Small size. The Cowon X7 is huge compared to most players, and it's fine by my standards. As long as it can fit cargo pants or slacks pockets, it's fine.

USB host

Text reader

Video

Specific OS, games, apps

Internet

A built-in microphone

Display: A must, at least 3", preferably more than 4".

UI/Controls: Tactical buttons or in combination with touch. I want to be able to change volume, skip songs and pause/play while the player is in my pocket

Battery life: At least 15 hours. Preferably with support for replaceable batteries